This invention relates to a film tip pulling device for pulling out the leading end of a rolled film in a patrone through its inlet/outlet.
Exposed film in a patrone is pulled back into the patrone. To develop the film, the patrone is set in an automatic developing device with the tip of the film pulled out of the patrone through its inlet/outlet.
Unexamined Japanese patent publication 4-120537 discloses a method of pulling a film out of a patrone through its inlet/outlet. In this method, the film winding spool provided in the patrone is rotated in the direction opposite to the film take-up direction to push the film tip out of the patrone through the film inlet/outlet.
In the arrangement disclosed in Examined Japanese utility model publication 55-16265, the film tip is pulled out by inserting a film puller into the patrone through its film inlet/outlet.
In the arrangement disclosed in unexamined Japanese patent publication 55-35353, tips of first and second film pulling plates are inserted into a patrone through ts film inlet/outlet; the first pulling plate is inserted into the patrone by rotating the spool of the patrone in the film take-up direction; the spool is stopped upon detection of a sound produced when the film tip passes the tip of the second pulling plate; the spool is rotated in the film unwinding direction thereafter; the film is sandwiched between the first and second pulling plates, and the film tip is pulled out by pulling out both pulling plates simultaneously.
The method in which the film tip is pulled out by rotating the spool in the unwinding direction can be used advantageously for film patrones having the function of pulling out the film tip, such as those disclosed in unexamined Japanese patent publication 2-124564 and U.S. Pat. No. 4,423,943. But, for patrones having no such function, it is difficult to pull the film out of the patrone through its inlet/outlet due to a curling tendency of the film because the film is stored in a rolled state.
In the method in which a film puller is used, the film tip has to be pulled out manually. Thus, this method is inefficient and less reliable. There is also the possibility of excessively pulling out the film.
An object of this invention is to provide a film tip pulling device which can automatically pull out the tip of film wound in a patrone only by a necessary length with high reliability without the need to rotate the spool or detect any sound.